Cooling arrangements for valves

ABSTRACT

An arrangement for cooling the collector of a travelling wave tube includes a heat sink which is connected via good thermally conductive collets to the collector. The collet comprises a collet jaw, which is in close contact with the collector, and an adjustable collet shoe which is slidably situated between the collet jaw and the heat sink. The arrangement allows lateral and angular displacement of the collector relative to the heat sink without degradation of the heat transfer properties.

[s 1 COOLHNG Aamomwwrs so VALVES 72 Inventor: tthew Campbell Kennedy,Chelm'sford,

England V {73] Assignee: English Electric VaiveCompany Limited,

London, England [22] Filed: Sept. 10, 1970 21 Appl. No.: 71,136

[30] Foreign Application Priority Data Sept. 12, 1969 Great Britain..45,047/69 52] U.S.Cl. .;..3113/46 [51] lint. Cl ...lillilllj 25/00[58] lField oiScarcli ..3l3/46 [56] References Cited UNITED STATESPATENTS 3,553,952 1/1971 Forbes .,,....313/46 Primary Examiner-Roy LakeAssistant Examiner-Darwin R. Hostetter Attorney-Baldwin, Wight and Brownthe heat sink without degradation of the heat transfer properties.

a claims, 1 Hm COOLING ARRANGEMENTS FOR VALVES This invention relates tocooling arrangements for valves and more particularly to arrangementsfor the conduction cooling of the collectors of travelling wave tubes.

It is frequently desirable to cool the collector of a travelling wavetube which is operating at an input power level greater than a fewwatts. I

One method which has been used to provide suitable cooling in such casesconsists of providing a heat conduction block which is attached to oneend of the travelling wave tube focusing mount. This block, within whichthe travelling wave tube is located, serves to conduct the heat from thecollector and the block may be attached to an external radiator ofadequate dimensions for the heat to be removed therefrom by naturalconvection. This arrangement is a satisfactory one provided thetravelling wave tube and its focusing mount are supplied as an integralpackage, for in this case the collector may be accurately andpermanently aligned with the focusing mount when' the block is securedto the focusing mount during final assembly of the components. Howeverin most applications it is preferred that the travelling wave tube bereplaceable within its mount in situ, because such tubes have a limitedoperating life. This avoids the need to disconnect waveguide connectionsand power supply leads to the mount when the travelling wave tube needsto be replaced.

Interchangeability of the travelling wave tube with its mount imposesspecial conditions on the design and construction of the block whichmust be such as to allow a quick, simple and easy insertion and removalof the tube to reduce the possibility of damage to the tube duringhandling and to minimize the time during which the equipment is not inoperation. In addition means must be provided for positioning thetravelling wave tube accurately with respect to its focusing mount. itis desirable to align the travelling wave tube accurately with thefocusing mount, since this makes a reduction in operating helix currentpossible (the common form of travelling wave tube in which the slow wavecircuit is a helix is, for the moment, assumed), thereby prolonging thelife of the travelling wave tube by reducing its operating temperature.The provision for fine adjustment of the tube position is also desirablebecause it permits some relaxation of the alignment requirements of theinternal tube electrodes during manufacture, which are in any casesevere.

The object of this invention is to provide, for a travelling wave tube,a cooling arrangement which whilst providing efficient cooling allowsadjustment of position of the travelling wave tube.

According to this invention a cooling arrangement for the collector of atravelling wave tube includes a block of material of good thermalconductivity, containing an aperture into which the collector may beinserted, and a plurality of collet members arranged to grip thecollector when it is positioned in the aperture, the collet members eachbeing made of material of good thermal conductivity and each having afirst part which is in said aperture and which abuts the collector, theabutting surface thereof being shaped so as to mate with said collectorsurface, and a second part which is positioned in a groove or channel insaid block such that it is in good thermal contact with said block andthe first and second collet member parts having flat mating surfaces soas to allow sliding contact therebetween.

if the mode of adjustment that is required for the travelling wave tuberequires both lateral and angular movements thereof then the arrangementshould employ two or preferably four collet members. If, however, solelylateral movement is required then the number of collet members used maydepart from two or four members.

Preferably the collet members are urged inwardly towards the aperture bymeans of springs under tension, the ends of a spring being attached totwo different collet members.

By a material of good thermal conductivity is intended a material, suchas a metal, whose thermal conductivity is significantly higher than thatof air. Similarly the expression good thermal contact" is intended tomean contact such as to provide thermal conduction substantially greaterthan that which occurs through air. A wide choice exists as regards thematerial for the thermally conductive elements. Copper and brass arematerials which have been used experimentally with very successfulresults. if a metal is used to assist thermal conduction through thesystem the sliding interfaces may with advantage be smeared with a goodthennally conductive oil or thin grease, which will act also as alubricant. The lubricant should preferably not be permitted to come intocontact with the travelling wave tube itself.

The invention is illustrated in and further described by way of examplewith reference to the accompanying drawing in which is shown adiagrammatic end view of one cooling arrangement in accordance with thisinvention.

Referring to the drawing, there is shown a collector l of a travellingwave tube, the collector being of cylindrical form and shown positionedin the center of an aperture 8 in a block 7. In thermal contact with thecollector are four collet members made of good thermally conductivematerial and having a first part, or collet jaw 2 so arranged and shapedas to encircle the collector l, but with a small gap between any onecollet jaw and adjacent collet jaws, to allow each collet jaw to seatproperly in contact with the collector 1. The collet jaws 2 are each ingood thermal contact with a movable second part 3 of the collet member,said second part 3 being a collet shoe. To

maintain the collet jaws 2 in close contact with the collector l a peg 4is inserted in each end face of each collet shoe 3 and a spring 5 intension attached between each adjacent pair of pegs 4. Each collet shoe3 is a close sliding fit within a groove or channel 6 within the body of'the block 7 of good thermally conductive material. The block 7 inpractice is secured to a travelling wave tube focusing mount (not shown)and may have suitable external finning (not shown) to assist heatdissipation to its surroundings. The collet shoes 3 have means (notshown) for having their position adjusted in the grooves or channels 6,and by these means adjustment of the lateral position and angularorientation of the collector 1 within the aperture 8 relative to thegood thermally conductive block 7,

and hence the focusing mount, may be effected.

Other arrangements according to this invention may also be used, forexample an arrangement using only two collet jaws which bear on oppositesides of the curved collector surface. In this case the surface of thecollet jaw in contact with the collector would encircle nearly half ofthe circumference of the collector, and as in the previous embodimenteach collet jaw would be in good thermal contact with a movable colletshoe.

The choice of the number of collet members used is not restricted to twoor four. However, both angular and translational movement of thecollector with respect to the block are attainable only witharrangements using either two of four collet jaws. With otherarrangements, for example one using three collet jaws, where each jawwould encircle approximately one-third of thecircumference of thecollector, the angular movement is not satisfactorily achievable andonly translational movement is possible whilst maintaining good thermalcontact between the collet jaws and the travelling wave tube collector.

I claim:

1. A cooling arrangement for the collector of a travelling wave tubesaid arrangement including a block of material of good thermalconductivity, containing an aperture into which the collector may beinserted, and a plurality of collet members arranged to grip thecollector when it is positioned in the aperture, the collet members eachbeing made of material of good thermal conductivity and each having afirst part which is in said aperture and which abuts the collector, theabutting surface thereof being shaped so as to mate with said collectorsurface, and a second part which is positioned in a groove or channel insaid block such that it is in good thermal contact with said block andthe first and second collet member parts having flat mating surfaces soas to allow sliding contact therebetween.

2. An arrangement as claimed in claim 1 wherein there are two colletmembers.

3. An arrangement as claimed in claim 1 wherein there are four colletmembers.

4. An arrangement as claimed in claim 1 wherein the collet 5 members areurged inwardly towards the aperture by means of springs under tension,the ends of a spring being attached to two different collet members.

1. A cooling arrangement for the collector of a travelling wave tubesaid arrangement including a block of material of good thermalconductivity, containing an aperture into which the collector may beinserted, and a plurality of collet members arranged to grip thecollector when it is positioned in the aperture, the collet members eachbeing made of material of good thermal conductivity and each having afirst part which is in said aperture and which abuts the collector, theabutting surface thereof being shaped so as to mate with said collectorsurface, and a second part which is positioned in a groove or channel insaid block such that it is in good thermal contact with said block andthe first and second collet member parts having flat mating surfaces soas to allow sliding contact therebetween.
 2. An arrangement as claimedin claim 1 wherein there are two collet members.
 3. An arrangement asclaimed in claim 1 wherein there are four collet members.
 4. Anarrangement as claimed in claim 1 wherein the collet members are urgedinwardly towards the aperture by means of springs under tension, theends of a spring being attached to two different collet members.